51571720021 has 8 divisors (see below), whose sum is σ = 51643597824. Its totient is φ = 51499877520.

The previous prime is 51571720009. The next prime is 51571720043. The reversal of 51571720021 is 12002717515.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 51571720021 - 2²¹ = 51569622869 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51571729021) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4278415 + ... + 4290451.

It is an arithmetic number, because the mean of its divisors is an integer number (6455449728).

Almost surely, 2^51571720021 is an apocalyptic number.

It is an amenable number.

51571720021 is a deficient number, since it is larger than the sum of its proper divisors (71877803).

51571720021 is a wasteful number, since it uses less digits than its factorization.

51571720021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17651.

The product of its (nonzero) digits is 4900, while the sum is 31.

The spelling of 51571720021 in words is "fifty-one billion, five hundred seventy-one million, seven hundred twenty thousand, twenty-one".